Processing apparatus for radiation detection devices



April 26, 1955 M. N. FAIRBANK 2,706,939

PROCESSING APPARATUS FOR RADIATION DETECTION DEVICES Filed Feb. 24, 1954 2 Sheets-Sheet l 23--\ JUL? 26 22 jf A V 94 O 12217 q INVENTOR FIG. 4 Z" ATTORNEYS April 26, 1955 M. N. FAIRBANK 2,706,939

PROCESSING APPARATUS FOR RADIATION DETECTION DEVICES Filed Feb. 24, 1954 2 Sheets-Sheet 2 R O T N E V N FIGS FIG. 6

ATTORNEYS 2,706,939 Patented Apr. 26, 1955 PROCESSING APPARATUS FOR RADIATION DETECTION DEVICES Murry N. Fairbank, Belmont, Mass., assignor to Polaroid Corporation, Cambridge, Mass., a corporation of Delaware Application February 24, 1954, Serial No. 412,264

15 Claims. (Cl. 9589) This invention relates to' apparatus for processing photosensitive'film units such as radiation-sensitive products in the nature of dosimeters of the character which utilize photosensitive materials for detecting, indicating, recording and measuring such radiation.

One embodiment of a film unit in the nature of a dosimeter and which is particularly adapted for processing by the devices set forth herein makes use of a releasably sealed envelope which carries, within its interior, photographic materials, including a photosensitive element and a rupturable container holding a photographic processing composition. The wall members of the envelope are substantially impervious to actinic light, liquid and vapor but are formed of materials which will transmit the nuclear radiation to be detected. Processing of a dosimeter of this character is effected by the application of pressure to opposite sides of the envelope in a manner to effect the rupture of the container therein and the appropriate spreading of its discharged liquid within the envelope.

An object of the invention which, as noted, is concerned with means for processing photosensitive dosimeters of the character described as individually comprising a lighttight envelope enclosing at least a photosensitive element and a rupturable container holding a liquid composition, resides in the provision of a simple, inexpensive and lightweight processing apparatus or device making use of a housing structure within which a dosimeter is carried and from which the dosimeter is withdrawable, a pair of constantly urged-together pressure-applying elements mounted within the housing structure and engageable with opposite sides of a dosimeter loaded into the structure and between which the dosimeter is movable for processing, means for opening and closing the housing structure comprising a movable member thereof, and cam means, associated with the housing structure, for effecting the separation of the pressureapplying members when the movable member is moved to open the housing structure for access.

Other objects of the invention are to provide processing apparatus of the character set forth wherein one of said pressure-applying elements is provided by spring means and said cam means is engageable with the spring means, as well as to provide processing devices wherein said cam means are carried by said movable member or wherein said cam means are fixed to a main portion of the housing structure and said spring means is carried by said movable member for contact with said carn upon movement of the movable member to open the housing structure.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the apparatus possessing the features, properties and the relation of components which are exemplified in the following detailed disclosure, and the scope of the application of which will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawings wherein:

Figure 1 is a plan view of a preferred embodiment of a dosimeter processing device or apparatus which forms the subject matter of this invention;

Fig. 2 is a longitudinal sectional elevation of the device of'Fig. l;

Fig. 3 is a detailed plan view of one of the spreader elements employed with the device of Fig. 1; P Fig. 4 is a side elevation of the spreader element of Fig. 5 is a perspective view of another embodiment of a dosimeter processing device or apparatus;

Fig. 6 is a plan view of a receptacle or housing member employed in the device of Fig. 4;

Fig. 7 is a plan view of an envelope dosimeter of the 10 type with which the processing devices of Figs. 1 and 4 are usable; and

Fig. 8 is a sectional elevation taken on the line 88 of Fig. 4.

While the present invention is unconcerned with radiation-detection devices per se, it is nevertheless believed that a description of the construction of a dosimeter will assist in understanding the nature, operation and utility of the processing devices disclosed in Figs. 1 through 6 of the drawings. One embodiment of dosimeter which is particularly adapted for processing by the apparatus set forth herein is indicated by the general reference numeral 70 (Figs. 7 and 8) and comprises an envelope formed of outer wall members 71 and 72 which are releasably secured together, by means of a strippable adhesive bond,

along the longitudinal edges thereof and also transversely of the wall members at one end thereof, as well as at a position preferably, although not necessarily, somewhat removed from the other end. This bond is adapted to provide a seal between the layers which is impervious to liquid and to light of a wavelength actinic to photosensitive materials within the envelope 70 and is shown in Fig. 7 at 73 as extending over an area lying between the rectangular marginal outline of the envelope as therein illustrated and the dotted line parallel to said outline.

By this arrangement it will be apparent that each layer 71 and 72 providing a wall member will have a portion at one end which is unconnected to the other wall member. These portions 78 and 79, in the form of exten sions, are in fact leaders which provide means to facilitate handling of the photosensitive unit, as well as means to assist in stripping the layers so that they may be placed in spread-apart condition after processing.

The envelope wall members 71 and 72 are each formed of a sheet material which is substantially impervious to actinic light, liquids and vapor, while being capable of transmitting nuclear radiation to be detected, i. e,, shorter wavelength radiation including X-rays and gamma rays. A print-carrying or print-receiving element 75, a rupturable container 77 for a liquid processing composition and a photosensitive element 74 are located within the interior of the envelope and are suitably secured to the inner surfaces. of the wall members 71 and 72, as shown. Photosensitive element 74 comprises one or more strips of a photosensitive material, such as silver halide, while the print-carrying or print-receiving element 75 may comprise a suitable sheet material, such as baryta paper. In the arrangement shown, the print-carrying element 75 is in superposed relation with the photosensitive element 74, while container 77 is located adjacent the end of the print-receiving element 75 which is positioned the nearest to the leader means of the dosimeter envelope.

A substantially liquid-impervious sheet material, similar to that used for forming the envelope wall members 71 and 72, is employed for container 77 whereby the container is adapted to hold a processing liquid. One example of a processing liquid usable for carrying out a silver halide transfer process comprises a silver halide developer and a silver halide fixer, both in solution in the liquid. The container 77 is positioned to extend transversely of the print-carrying element and is provided with a rupturable seal adjacent the print-carrying element whereby pressure applied to opposite sides of the dosimeter envelope will effect the rupture of this seal and the discharge of the liquid content of the container for spreading between and in contact with the superposed paint-receiving element 75 and the photosensitive element Dosimeters of the character illustrated in Figs. 7 and 8 are intended to utilize a photographic transfer process in determining the extent to which the dosimeter has been acted upon by nuclear radiation of the type to be detected. As previously pointed out, the nuclear radiation to be detected will penetrate through the envelope. Radiation of this character will form latent image in the photosensitive materials of the photosensitive element 74. The processing liquid when spread between and in contact 'With the print-carrying element and the photosensitive element is adapted to develop latent image in the photosensitive element to silver and to form, by transfer, a reverse print thereof on the print-carrying element. Following formation of the reverse image, the envelope layers are peeled or stripped apart. The density of the transfer image is utilizedto determine the extent of radiation dosage received by the dosimeter by comparing this density with a standard which is representative of print densities obtained by exposing photosensitive materials similar to those employed in the dosimeter to predetermined dosages of nuclear radiation.

The principles of a transfer process, as well as film structures and dosimeters suitable for use in the invention, are set forth in United States Patent No. 2,543,181, issued February 27, 1951, to Edwin H. Land for Photographic Product Comprising a Rupturable Container Carrying a Photographic Processing Liquid; United States Patent No. 2,634,886, issued April 14, 1953, to Edwin H. Land for Collapsible Fluid Container, and copending application Serial No. 218,042, filed March 28, 1951, by Murry N. Fairbank and William A. Shurclifi for Radiation Detection Devices. The last-noted application is specific to dosimeter construction of the general nature of the dosimeter illustrated in Figs. 7 and 8 herein. Patents Nos. 2,543,181 and 2,634,886 and said copending application include detailed descriptions of film units comprising a photosensitive element and a print-carrying element which are adapted to contain all of the photographic materials needed to process the unit. Also, the just-mentioned patents and copending application are detailed as to containers for holding processing materials and further include descriptions of liquid processing compositions usable with such units. The practices, photographic materials and compositions described in said Patents Nos. 2,543,181 and 2,634,886 and said copendingapplication are generally suitable for carrying out the present invention and special reference to the details thereof are made in said patents and copending application.

The dosimeters described herein are intended to be carried on the person and to be processed at the instant that the possessor of the device wishes to determine if he has been subjected to unsafe radiation conditions. Consequently, the dosimeters are relatively small. For example, the complete envelope in any of the embodiments heretofore disclosed may have dimensions of about 3 inches by 1 inch or even smaller.

Under the just-noted circumstances wherein the dosimeter is literally intended to be processed at an instants notice, it is desirable to provide processing means of simple and lightweight construction for association with the dosimeter. Preferably, the processing apparatus or device should be of a size and weight such that it may be carried on the person, as by attachment to an article of clothing, or by suspension around the neck from a chain or ribbon or cord as in the case of the so-called military dog tag, or even carried in a pocket. It is desirable that such an apparatus, in addition to providing processing means, should also serve several other functions.

For example, the processing apparatus should be in the nature of a holder or carrier for storing or holding one or more dosimeters. Likewise, the processing holder should be able to protect the carried dosimeters from dirt, moisture, such as perspiration, and the like, while guarding each dosimeter carried therein against the application of forces which would rupture the liquid container of said dosimeter and while maintaining the dosimeter in a generally flat condition ready for use. In addition, the holder should provide means for shielding the dosimeter from soft rays which might prematurely expose photosensitive materials within the dosimeter envelope.

One embodiment of a device or apparatus 10 for processing a photosensitive type of dosimeter is illustrated in Figs. 1 through 4 as comprising a main housing or open receptacle 11, of plastic, adapted to be closed by a closure or cover member 12 of sheet metal in the form of a plate which is hingedly connected at one end of the housing by means of a hinge pin 14 extending through the side walls of the receptacle 11. Receptacle 11 may also be formed of metal or wood or the like.

Pressure-applying means which are constantly urged into processing position are adapted to be provided within the housing of the apparatus. One member of such pressure-applying means comprises a spring unit 15 of suitable metal having a base provided with turned-up side walls, as illustrated in Figs. 2 and 3, with a fiat spring portion 16 which extends from the base and is free, for most of its length, of connection with the side walls of the unit. Spring portion 16 is provided at its free end with a rolled-over or rounded portion 17 adapted to provide one of the pressure-applying or spreader elements of the spreader unit. Unit 15 is seated in the receptacle 11 with the base thereof fixed to the bottom of the receptacle by means of a rivet or other fastening 19. As clearly shown in Fig. 2, spring 16 is constantly urged away from the bottom of the housing 11.

The other element of the pressure-applying means is provided by the hinged cover or closure 12 and is itself a rolled-over or rounded portion 18 located at one end of the cover. The rounded portion 18 also functions as part of the means for hinging cover 12 to the receptacle portion 11 of the device and has the pin 14 extending through the rounded portion and engaged thereby.

It is to be noted that the device 10 is so constructed that spring force developed by spring 16 is self-contained in the spring unit 15 and also that a design is employed where the push of the spring when in operating condition is re strained by metal, i. e., the side walls of the unit 15, the hinge pin 14 and the rounded pressure-applying member 18 of the cover plate 12. Such arrangement is generally preferred, especially in instances Where there is employed a plastic housing of a nature tending to distort or deform under frequently if not constantly applied loads. However, the invention includes within its scope the use of a flat spring similar to the spring unit 15 but wherein the turned-up side walls or side portions such as provided on the unit 15 are omitted.

As may be noted, closure 12 extends from the hinge or forward end of the processing device to a position beyond the rear end thereof where it is bent over to provide a resilient fastener or latch 20 which is in releasable pressure contact with the exterior surface of the back transverse Wall 21 of the housing portion 11 and functions to hold the closure 12 in covering position.

The side walls of the housing 11 are extended beyond the transverse rear wall 21 to provide a pair of spacedapart extensions 22 which have holes 23 extending transversely therethrough. Extensions 22 provide means for attaching an endless chain or other endless and flexible carrying means 24 to the device for permitting its suspens1on around a persons neck. In forming the latch 20, a portion 25 thereof is bent into a U shape to provide hook means which extend transversely of the cover plate 12. Chain 24 is adapted to extend through the U-shaped portion 25 or hook means of the latch 20 and holes 23 in the extensions 22. This arrangement provides a safety lock which prevents accidental opening of the cover 12 when the processing device is suspended by the chain 24. Since the cha n 1s relatively long, it is a simple matter to hold the device 10 in the hand and free the chain of its Weight whereby the cover 12 is released and opened by pushing the latch 20 away from the receptacle or housing portion 11. Chain 24 may be removed from the U-shaped portion 25 or hook means if desired after partially opening the closure or cover plate 12.

Other means fall within the scope of the invention for the purpose of facilitating the carrying of the device on the person or its attachment to an article of clothing such, I

for example, as a bail member attached to the extensions 22 or a pin or other means.

Both the housing 11 and cover 12 are provided with recesses in their inner surfaces. A lead shield 27, suitable for controlling the passage of radiation through the device, is mounted within each of said recesses.

The housing portion 11 is effectively a structure which has two side walls and a back wall whereby it is open at its forward end to permit withdrawal of a dosimeter therethrough. The pressure-applying elements 17 and 18 provide a yieldable or resilient closure at the forward end of the device 10 through which a dosimeter is withdrawable.

A dos1meter, when loaded for processing into the device 10, is adapted to be seated on the spring unit 15 with the leader portion thereof extending between the pressureapplying elements 17 and 18. In order to insert the leader of a dosimeter between the elements 17 and 18, it becomes necessary to depress the spring 16 while holding the box open. To facilitate this operation, means are provided upon the closure member 12 for automatically depressing the spring 16 upon opening of the cover. These means comprise cams 26, shown particularly well in Figs. 1 and 2, which extend outside of the rolled portion providing the spreader of pressure-applying element 18 on the cover and are brought into bearing with the pressure-applying element 17 as the box is opened to depress spring 16.

Operation of the processing device will now become apparent. As the cover 12 is fully opened, cams 26 are brought into bearing contact with the spring-actuated pressure-applying element 17 and efiect a separation from the pressure-applying element 18 whereupon a dosimeter is placed in the housing 11 with the leader portion thereof extending outwardly of the housing and between the held-apart pressure-applying elements and with the body of the dosimeter seated upon the base and spring of the spring unit 15. Following this, the cover is closed so that the spring catch locks the cover in the position shown in Fig. 1. As the cover is moved to its closed position, earns 26 are moved out of bearing contact with the pressure-applying element 17 and permit the opposite sides of the leader portion of the dosimeter to be engaged in bearing contact with the two pressure-applying members.

For processing the dosimeter, the device is held by one hand while the leader portion which extends from the device is grasped in the other hand and pulled to effect the withdrawal of the dosimeter from the device while carrying out the processing thereof. The spring pressure generated by the spring 16 is sufficient to rupture the container within the dosimeter envelope as the envelope is drawn between the pressure-applying elements 17 and 18, which also effect the spreading of the liquid contents of the container between the layers of the dosimeter. After the dosimeter has been withdrawn from the processing device and following an imbibition period of about a minute, it is peeled apart for the purpose of obtaining the photographic record of the intensity of the radiation to which the dosimeter has been subjected.

It will be understood that the dosimeter processing apparatus 10, as well as the modified processing apparatus of Fig. 5, may have a dosimeter mounted therein with the leader portions 78 and 79 folded over upon one side of the dosimeter envelope for storage or carrying purposes. However, when the dosimeter is to be processed, it will be necessary toremove it from the apparatus and mount it for processing as previously described and with the leader portion thereof extending between the pressure-applying members.

In Figs. 5 and 6 the construction principles heretofore explained for effecting the automatic separation of the pressure-applying or spreader members of a dosimeter processing device are disclosed in a further embodiment of the invention. In Fig. 5, the processing device is generally indicated by the reference numeral 30 as comprising a main receptacle or housing portion 31 within which the dosimeter is adapted to be mounted and a tubular type of closure or cover means 32 for closing the receptacle 31. By this type of construction, the receptacle 31 is of the nature of a drawer which is slidable within the cover means or closure member 32.

Drawer 31 is preferably formed of a suitably rigid material such as metal and, instead of having the selfcontained spring unit 15 of Fig. 1 mounted therein,

makes use of a fiat spring 35. Spring 35, which is similar to the spring unit 15 except that it omits the bent-up side walls of the spring unit, is fixedly mounted within the drawer 31 with rivets or the like. It is to be understood, however, that the embodiment of the invention disclosed in Figs. 5 and 6 may be practiced by mounting within the drawer 31 a spring unit 15 similar to that disclosed in conjunction with the device 10.

Spring 35 has a rolled-over curved surface at its free end to provide a pressure-applying element 37. In this instance, the other pressure-applying element 38 is fixed between the sides of the drawer-type receptacle 31 for bearing contact with the spring-actuated pressure-applying element 37. As may be noted, member 38 has a suitably rounded surface for cooperation with the pressure-applying element 37.

As indicated, the closure or covering 32 for the drawer or main receptacle 31 is open at both ends. The end of the drawer 31 which is most distant from the pressureapplying elements 37 and 38 is provided with a face plate 33 which is adapted to bear against the outer surface at the end of the covering 32 when the drawer is pushed inwardly of the covering 32 whereby to close this end of the processing device. The pressure-applying elements 37 and 38 are adapted to provide the usual yieldable closure for the other end of the processing device when the drawer is in closure position.

In the embodiment of the invention illustrated in Fig. 5, the means for separating the spreader members or elements are operable upon pulling out the drawer-type receptacle 31. These means, as shown in Figs. 5 and 6, comprise tabs 34 which extend from opposite sides of the fiat spring 35 and through cutaway portions in the side walls of drawer 31 to permit cooperation with cams 39 fixed to the closure 32 on opposite sides and at the end thereof contactable by the face plate 33.

This construction is arranged so that as the drawer 31 is pulled to an open position, the tabs 34 therein ride under cams 39 whereby to effect the separation of the spring-actuated pressure-applying or spreader element 37 with respect to the fixed pressure-applying member 38. Also, tabs 34 are adapted to extend into slots 36 provided in the side walls of the closure 32 for free sliding movement therein. It will be apparent that as the drawer is closed, tabs 34 are freed from contact with the cams 39 to permit the spring-actuated pressure-applying element 37 to be moved into contact with the fixed pressure-applying element or into contact with the opposite sides of a dosimeter placed within the processing device.

It may also be pointed out that slots 36 are terminated at a location near the end of the closure means 32 which is adapted to be contacted by the face plate 33 whereby to provide stop means for retaining the drawer 31 within the closure means 32.

A suitable bail 40, secured to closure member 32 or other carrying means, including a flexible endless chain or cord or a fastening means such as a pin, is intended for use with the processing device 30. In the case of the bail 40, it is also within the scope of the invention to so con struct it as to utilize it as a latch means for securing the drawer 31 in closed position.

Lead shields, similar to the shields 27, are intended to be associated with the processing device 30 of Fig. 5 and are carried by the closure means 32 thereof.

It may be further noted in regard to the device 30 that the spring-actuated pressure-applying element is carried by the movable member of the processing device whereas the spring-actuated pressure-applying element of the device 10 of Fig. 1 is carried by the member thereof which is held stationary relative to the movable member. Furthermore, the cam means of the device 30 are carried by the member which is stationary with respect to the movable member of the device as opposed to the construction employed in the device 10.

In view of the foregoing description of the device 30 of Figs. 5 and 6 as well as the processing device 10 of Figs. 1 through 4, it will be apparent that operation of the device 30 for loading, storing and processing a dosimeter will be similar to the operations heretofore set forth.

Since certain changes may be made in the above apparatus without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. An apparatus for processing a photosensitive film unit of the type having an elongated envelope and at least a photosensitive element and a rupturable container carried within the envelope and positioned relative to each other so that liquid discharged from said container upon rupture thereof may be spread over said photosensitive element, said apparatus comprising a receptacle type of member in which the film unit is adapted to be supported, said receptacle member having an open end portion and an open top portion, a closure member providing means for closing the top portion of said receptacle member, means connecting said members together whereby one of said members is mounted for movement relative to the other of said members for opening and closing the top portion of the receptacle member, a first pressure-applying element carried by one of said members and a second pressure-applying element carried by one of said members, said pressure-applying elements having rounded surfaces and being so located as to have said surfaces in superposed relation when said members are in position to close the top portion of said receptacle member, spring means forming a part of one of said pressure-applying elements for urging it into contact with the other pressure-applying element, said spring means being carried by said receptacle member, cam means for forcing said spring means and the pressure-applying element forming a part thereof away from the other pressureapplying element to sep arate said pressure-applying elements whereby to permit insertion of a portion of said film unit between the pressure-applying elements for engagement with opposite sides of said film unit, said cam means being carried by one of said members and being operable to separate said pressure-applying elements by the movement of the movably mounted member of said pair of members to a position for gaining access to the top portion of said receptacle member, said cam means also being operable to release said spring means upon the movement of said movably mounted member to a position for closing the top portion of said receptacle member, and said pressure applying elements providing means forming a yieldable closure at one end of said device through which a film unit loaded into the device may be withdrawn and also providing suificient pressure to rupture the container of the film unit and spread its liquid content between the layers thereof upon the withdrawal of the film unit from said device.

2. Apparatus as defined in claim 1 for processing a film unit wherein said cam means is carried by said closure means.

3. Apparatus of the character defined in claim 1 for processing a film unit wherein said cam means is carried by the movable member of said pair of members constituted by said receptacle member and said closure member.

4. Apparatus as defined in claim 1 for processing a film unit wherein said closure member is the movably mounted member of said pair of members.

5. Apparatus as defined in claim 1 for processing a film unit wherein said closure member is hingedly connected to said receptacle member and wherein said closure member carries one of said pressure-applying elements.

6. Apparatus as defined in claim 1 for processing a film unit wherein said closure member is hingedly connected to said receptacle member and wherein said closure member carries said cam means.

7. Apparatus as defined in claim 1 for processing a film unit wherein said closure member is hingedly connected to said receptacle member and wherein said closure member carries one of said pressure-applying elements and also carries said cam means.

8. Apparatus as defined in claim 1 for processing a film unit wherein said closure member is movable and is provided with cam means comprising fingers engageable in bearing contact with the pressure-applying element which includes said spring means upon the movement of said closure member to a position to open the top portion of said receptacle.

9. Apparatus as defined in claim 1 for processing a film unit wherein said pressure-applying element actuated by said spring means is carried by said receptacle member, said closure member is hingedly connected to said receptacle member and carries the second of said pressureapplylng elements as well as said cam means, said cam means comprising fingers engageable in bearing contact with said pressure-applying element which is actuated by said spring means upon movement of said closure member to a position to open the top portion of said receptacle.

10. Apparatus as defined in claim 1 for processing a film unit wherein said cam means are provided upon that member of said pair of members constituted by said receptacle member and said closure member which remains relatively stationary with respect to the movable member of said pair.

ll. Apparatus as defined in claim 1 for processing a film unit wherein said receptacle member is movable relative to said closure member.

12. Apparatus as defined in claim 11 for processing a film unit wherein said closure member is of generally tubular shape and said receptacle member is slidable within said tubular member from a position wherein the top portion of the receptacle member iscovered by said closure member to a position wherein the top portion of said receptacle member is substantially uncovered and free of the closing action of said closure member whereby to gain access to said receptacle member.

13. Apparatus as defined in claim 12 for processing a film unit wherein said receptacle member carries both pressure-applying elements.

14. Apparatus as defined in claim 1 for processing a film unit wherein said receptacle member is slidably mounted within said closure member and wherein said receptacle member carries both said pressure-applying elements and said closure member carries said cam means for effecting the separation of said pressure-applying elements.

15. Apparatus as defined in claim 14 for processing a film unit wherein said pressure-applying element which includes said spring means is provided with tablike extensions releasably engageable by said cam means upon movement of said receptacle member relative to said closure member to a position to gain access to the open top portion of the receptacle member.

No references cited. 

1. AN APPARATUS FOR PROCESSING A PHOTOSENSITIVE FILM UNIT OF THE TYPE HAVING AN ELONGATED ENVELOPE AND AT LEAST A PHOTOSENSITIVE ELEMENT AND A RUPTURABLE CONTAINER CARRIED WITHIN THE ENVELOPE AND POSITIONED RELATIVE TO EACH OTHER SO THAT LIQUID DISCHARGED FORM SAID CONTAINER UPON RUPTURE THEREOF MAY BE SPREAD OVER SAID PHOTOSENSITIVE ELEMENT, SAID APPARATUE COMPRISING A RECEPTACLE TYPE OF MEMBER IN WHICH THE FILM UNIT IS ADAPTED TO BE SUPPORTED, SAID RECEPTACLE MEMBER HAVING AN OPEN END PORTION AND AN OPEN TOP PORTION, A CLOSURE MEMBER PROVIDING MEANS FOR CLOSING THE TOP PORTION OF SAID RECEPTACLE MEMBER, MEANS CONNECTING SAID MEMBERS TOGETHER WHEREBY ONE OF SAID MEMBERS IS MOUNTED FOR MOVEMENT RELATIVE TO THE OTHER OF SAID MEMBERS FOR OPENING AND CLOSING THE TOP PORTION OF THE RECEPTACLE MEMBER, A FIRST PRESSURE-APPLYING ELEMENT CARRIED BY ONE OF SAID MEMBERS AND A SECOND PRESSURE-APPLYING ELEMENT CARRIED BY ONE OF SAID MEMBERS, SAID PRESSURE-APPLYING ELEMENTS HAVING ROUNDED SURFACES AND BEING SO LOCATED AS TO HAVE SAID SURFACES IN SUPERPOSED RELATION WHEN SAID MEMBERS ARE IN POSITION TO CLOSE THE TOP PORTION OF SAID RECEPTACLE MEMBER, SPRING MEANS FORMING A PART OF ONE OF SAID PRESSURE-APPLYING ELEMENTS FOR URGING IT INTO CONTACT WITH THE OTHER PRESSURE-APPLYING ELEMENT, SAID SPRING MEANS BEING CARRIED BY SAID RECEP- 